In connection with cable television systems, it is necessary to provide one or more power supply units for the CATV system which interconnect with a line carrying the usual available utility or power company line voltage of 115 volts AC (115 VAC) and converts the same to the normal lower desired voltage, preferably 60 VAC, although in some instances a differing CATV voltage may be employed, as 30 VAC.
The conversion is effected by transformer circuitry of generally known nature, and again preferably employs a ferroresonant transformer to step down the voltage as well as to smooth out transient power swings and other irregularities. Circuit time delay means may be provided to enhance the in-use effectiveness of the power supply, which may not be always quickly o readily accessible.
Such a CATV power supply must be appropriately mounted for security, ruggedness, and especially adequate cooling, among other desired features. Conventionally, as with much electrical equipment, CATV power supplies are mounted within sheet metal cabinets with doors or removable covers, and the same are louvered in usual manner as by partially striking out portions of the sheet metal so as to provide ventilation to the transformer circuitry.
Illustrative louvered sheet metal power supplies of this type are the Model PS-60 marketed by RMS Electronics, Inc., Bronx, NY or Model NS 30/60-15 of Power Technologies Inc., Redmond, WA.
While such sheet metal enclosures are serviceable, the same possess inherent disadvantages of lack of ruggedness by virtue of the relatively thin bent sheet metal housing, and also have substantially open access to the atmosphere, moisture, and particulate debris by virtue of the louvered vent openings, thereby minimizing the service life of the transformer components, but also of the housing itself. Indeed, existence of openings such as louvres also facilitates tampering with and damaging the power supply housing by the use of prying tools in the housing openings.
Additionally, such housings do not lend themselves for ready adaptation to diverse mountings as may be required in one or more given installations.